Cátia Nunes da Cunha

Biodiversity and its conservation in the Pantanal of Mato Grosso, Brazil

Abstract.The Pantanal of Mato Grosso, Brazil, is famous for its luxurious plant and animal life. We combine a literature review with recent work and show that species diversity is large but that most major plant and animal groups contain a large number of not wetland-specific species that depend on permanently terrestrial habitats within the Pantanal, or are restricted to dry areas during the low water period. These species occur also in the neighbouring biomes of Cerrado, Amazon Forest or Chaco. Until now, very few endemic species have been described, however, there are large populations of species in the Pantanal that are considered rare or endangered in South America. The number of trees adapted to long term flooding is low in comparison with the Amazon River floodplain. We hypothesize that the reason for the lack of local endemisms and the occurrence of a large number of species with a large ecological amplitude is the climatic instability of the region of the Pantanal, which suffered severe drought during glacial periods. The instability of the actual climate, which is characterized by multi-annual wet and dry periods, has a strong impact on distribution, community structure and population size of many plant and animal species and hinders spatial segregation of populations. The dependence of the system on the flood pulse makes the Pantanal very vulnerable to human induced changes in hydrology and the predicted changes in global climate.

Unidades fitofisionômicas em mesoescala no Pantanal Norte e suas relações com a geomorfologia

The purpose of this work was to characterize and quantify phytophysiognomic units at mesoscale and evaluate their relationships with flood intensity, flood duration and topography. The study was conducted at a 25 km2 Long-Term Sampling Site (LTSS), located within the floodplain of the Cuiaba River in the Pantanal of Mato Grosso. The phytophysiognomic units were determined from the supervised classification of CBERS 2B sensor CCD satellite images. The maps of flood intensity, flood duration and of topography were generated from the spatial interpolation of planialtimetric field surveys. Four phytophysiognomic units were identified; Campo inundavel (flooded grassland) was the unit with the largest area of occurrence, followed by Cordilheiras (dense arboreal savanna), Landizal (seasonally flooded evergreen forest), and Cambarazal (monodominant Vochysia divergens Pohl. forest), respectively. Campo inundavel is distributed mainly in areas of high flood intensity and duration and low topographic positions. Cambarazal predominates in areas of medium flood intensity and duration and intermediate elevation, Landizal in areas of high flood intensity and duration and low topographic position, whereas Cordilheiras are characterized by low flood intensity and duration and location in higher elevations. Statistical tests indicated that flood intensity is the main factor responsible for the mesoscale distribution of phytophysiognomic units in the northern Pantanal.

Arthropod biodiversity in the canopy of Vochysia divergens (Vochysiaceae), a forest dominant in the Brazilian Pantanal.

The canopy of an invasive tree species in the Pantanal floodplains, Vochysia divergens Pohl (Vochysiaceae; height 12 m) was sprayed once with 5% synthetic pyrethrum during the dry, non-flooded season near Poconé, Mato Grosso. About 4200 arthropods collected (43.7 ind./m 2) represented 14 orders. The Hymenoptera dominated (21.4 ind./ 2 ; mostly ants), followed by Coleoptera, Araneae and Diptera (85% of the total catch). Of the 26 Coleoptera families (6.2 ind./ 2) the Curculionidae, Scolytidae, Elateridae and Dryopidae were most abundant (70% of the total catch), and on trophic level the herbivores dominated (42%). This is the first quantitative canopy study of a tree species in the northern Pantanal floodplains. The type of data needed on arthropods from tree canopies in future studies to aid in the management and conservation of Pantanal floodplains is discussed.

Stability and generalization in seed dispersal networks: a case study of frugivorous fish in Neotropical wetlands

When species within guilds perform similar ecological roles, functional redundancy can buffer ecosystems against species loss. Using data on the frequency of interactions between fish and fruit, we assessed whether co-occurring frugivores provide redundant seed dispersal services in three species-rich Neotropical wetlands. Our study revealed that frugivorous fishes have generalized diets; however, large-bodied fishes had greater seed dispersal breadth than small species, in some cases, providing seed dispersal services not achieved by smaller fish species. As overfishing disproportionately affects big fishes, the extirpation of these species could cause larger secondary extinctions of plant species than the loss of small specialist frugivores. To evaluate the consequences of frugivore specialization for network stability, we extracted data from 39 published seed dispersal networks of frugivorous birds, mammals and fish (our networks) across ecosystems. Our analysis of interaction frequencies revealed low frugivore specialization and lower nestedness than analyses based on binary data (presence–absence of interactions). In that case, ecosystems may be resilient to loss of any given frugivore. However, robustness to frugivore extinction declines with specialization, such that networks composed primarily of specialist frugivores are highly susceptible to the loss of generalists. In contrast with analyses of binary data, recently developed algorithms capable of modelling interaction strengths provide opportunities to enhance our understanding of complex ecological networks by accounting for heterogeneity of frugivore–fruit interactions.

Caracterização da flora e estrutura do estrato arbustivo-arbóreo de um cerrado no Pantanal de Poconé, MT

In wetlands as the Pantanal, the floristic composition and community structure respond primarily to the flood pulse and, in order to understand the species that enter this biome, these plant communities need to be floristically and structurally described. Therefore, the objectives of this paper are characterize floristic composition and vegetation structure on a cordilheira (paleolevees), in the Pirizal region, Nossa Senhora do Livramento County, MT; define the type of vegetation and determine whether there is a greater floristic similarity degree between the object of this study and other cerrado s.s. or cerradao areas in Central Brazil. 102 contiguous plots of 20 x 5 m were distributed systematically arranged in six transects towards edge-center-edge cordilheira, thus having a total area of 1,02 ha. For sampling purposes, only individuals with entire stem DBH > 3 cm including dead trees and palms. 82 different species of trees and shrubs were identified, which in turn were spread in 63 genera, 32 families and one unidentified species. Being 37 species characteristics of areas with cerradao, 19 of cerrado s.s., nine distributed both in areas of cerradao and in cerrado s.s., and 10% belonging to the Pantanal wetland environments. Comparing the studied area with other communities across the DCA, the results indicated the existence of two floristic groups relatively distinct, the first formed by areas composed of cerrado s.s. and the second by cerradoes areas. Among the areas formed by cerradoes, there was a separation of the sampled areas in the region of the Pantanal (wetlands) those occurring elsewhere in the Centro-Oeste (dry land). The vegetation on cordilheira showed greater floristic and structural relationship with cerradoes than with cerrado s.s. of west center region of Brazil, and may thus be characterized as a vegetation type of cerradao. The savannas of the Pantanal had a lower floristic relationship with other regions of the Centro-Oeste, this floristic heterogeneity may be related to the flood pulse which acts as a filter for most species in other areas of the Planalto Central.

Endophytic fungal communities of Polygonum acuminatum and Aeschynomene fluminensis are influenced by soil mercury contamination

The endophytic fungal communities of Polygonum acuminatum and Aeschynomene fluminensis were examined with respect to soil mercury (Hg) contamination. Plants were collected in places with and without Hg+2 for isolation and identification of their endophytic root fungi. We evaluated frequency of colonization, number of isolates and richness, indices of diversity and similarity, functional traits (hydrolytic enzymes, siderophores, indoleacetic acid, antibiosis and metal tolerance) and growth promotion of Aeschynomene fluminensis inoculated with endophytic fungi on soil with mercury. The frequency of colonization, structure and community function, as well as the abundant distribution of taxa of endophytic fungi were influenced by mercury contamination, with higher endophytic fungi in hosts in soil with mercury. The presence or absence of mercury in the soil changes the profile of the functional characteristics of the endophytic fungal community. On the other hand, tolerance of lineages to multiple metals is not associated with contamination. A. fluminensis depends on its endophytic fungi, since plants free of endophytic fungi grew less than expected due to mercury toxicity. In contrast plants containing certain endophytic fungi showed good growth in soil containing mercury, even exceeding growth of plants cultivated in soil without mercury. The data obtained confirm the hypothesis that soil contamination by mercury alters community structure of root endophytic fungi in terms of composition, abundance and species richness. The inoculation of A. fluminensis with certain strains of stress tolerant endophytic fungi contribute to colonization and establishment of the host and may be used in processes that aim to improve phytoremediation of soils with toxic concentrations of mercury.

Flood Tolerant Trees in Seasonally Inundated Lowland Tropical Floodplains

This chapter focuses on trees and their responses to flooding in large fresh water flood-pulsed ecosystems. The regularity and predictability of the flood pulse has allowed for the development of adaptations by which a large number of tree species are able to grow in ecosystems subjected to seasonally inundated sites. By comparing diversity and tree responses in four floodplain ecosystems on different continents, we attempt to improve our understanding of the factors influencing spatial distribution of plants, diversity of species and adaptations and thus contribute to our knowledge of tropical wetland ecology. In this way, we hope to assist in the successful restoration of degraded floodplains and promote the sustainable use and conservation of these highly valuable ecosystems.

Does Flood Pulsing Act as a Switch to Store or Release Sediment-Bound Carbon in Seasonal Floodplain Lakes? Case Study from the Colombian Orinoco-Llanos and the Brazilian Pantanal

Wetlands have been identified as key elements of global carbon budgets. Today, due to increasing anthropogenic carbon emissions, the carbon storage capacity of these ecosystems has become of global interest. The focus of this research was to determine the storage capacity and mechanisms of carbon sequestration of Neotropical seasonal shallow lakes (SSLs), assessing their flood pulse, biomass, geomorphology and sediment composition. We applied a standardized and extensive sampling to five SSLs from the Colombian Orinoco-Llanos and five from the Brazilian Pantanal, during both flooded and non-flooded seasons. We found that sediment organic carbon (SOC) storage capacity in SSLs is significantly driven by the number of flooded days (p-value = 0.0057) rather than by their biomass production. The Orinoco-Llanos and Pantanal lakes differ in morphology, and thus in their inundation patterns. SSLs of the Orinoco-Llanos are more concave, having a significantly higher number of flooded days/year than SSLs from Pantanal. These hydrologic differences affect SOC storage, resulting in a significantly higher SOC storage in SSLs from Orinoco-Llanos than in Pantanal. A synopsis of data from both regions suggests the existence of a critical threshold between “non-flooded season losses” and “non-flooded season storage” of SOC in SSLs in a range of 225–275 flooded days/year.